On 27.02.2017 16:37, Adrian Klaver wrote:
On 02/27/2017 07:03 AM, Sven R. Kunze wrote:
Why is this relevant for dates? I cannot see that dates are
timezone-influenced.
Per Tom's post, see points 2 & 3:
Maybe, I am on a completely wrong track here, but to me dates still
don't look timezone dependent. They are just dates and not times, aren't
they?
"* some of them depend on the current timezone (but I don't believe
date_in does);
* all of them depend on the current datestyle setting, eg to resolve
'02/03/2017';
* all of them accept strings with time-varying values, such as 'now'
or 'today'.
You could get around the second and third points with to_timestamp(),
but since the only variant of that is one that yields timestamptz and
hence is affected by the timezone setting, it's still not immutable.
"
Reading this through again, I got an idea:
Wouldn't it be possible to provide an immutable variant of to_timestamp
and to_date with a third parameter to specify the otherwise
setting-dependent timezone?
I still feel that a function is overkill for a simple text to date
conversion. Couldn't there be an IMMUTABLE modifier for an expression to
mark it as immutable?
Any thoughts on this?
"SELECT '2007-02-02'::date;" just works. It would be great if one could
define an index with the same ease. I already can see how our
application developers need constant reminders that "in case of dates,
use 'magic_function' first". If they don't, the application will suffer
from bad performance.
Best regards,
Sven
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